Field of the Invention
The present invention relates to a stacking apparatus, a feeding apparatus, and an image forming apparatus capable of stacking a sheet as an image forming target.
Description of the Related Art
Some image forming apparatuses such as a copying machine and printer have an arrangement which includes a sheet storage unit and a feeding unit such as a feeding roller for feeding sheets stored in the sheet storage unit, and feeds a sheet stored in the sheet storage unit to an image forming unit by the feeding unit. Recently, image forming apparatuses including a large-capacity sheet storage unit into which a large number of sheets such as thousands of sheets can be replenished are increasing in number. Also, in the recent printing market, needs for performing printing on elongated paper sheets longer than regular-size paper sheets such as A3 and A4 are increasing (for example, a book cover, facing pages of a catalogue, and POP advertisement).
In a conventional sheet feeding apparatus that supports elongated paper sheets, a plurality of paper stacking lifters which are independently operable are arranged, and removable partition plates are provided in common use. Each partition plate has a function of preventing stacked sheets from collapsing or mixing in size (Japanese Patent Laid-Open No. 2003-63719).
In a conventional arrangement, however, if a partition plate is removed when a user uses a paper stacking lifter on one side, he/she needs to attach the partition plate again, impairing usability. Moreover, if an elongated paper sheet is to be fed in a state in which the partition plate is always mounted, an internal atmosphere between the paper stacking lifters is blocked. That is, a recent feeding apparatus needs to support various paper types, and as measures against paper having a high friction coefficient among pieces of paper, such as coated paper in particular, an air flow may be generated inside by using, for example, a heat source such as a cassette heater, a fan, or the like. In the conventional arrangement, however, internal air permeability becomes deteriorated due to the partition plate, so heat or the internal air flow cannot be circulated well.